The present invention relates to a time base conversion apparatus for allowing exchange of signals between two systems having different time bases. In the prior art, for example, when obtaining a printed image from an NTSC television signal, a television signal of 1/30 sec carries information corresponding to an image of one frame, while the printer cannot complete printing thereof within 1/30 sec. A memory for storing the image of one frame, that is, a 1-frame memory, may be incorporated. However, the 1-frame memory must have a large memory capacity and is therefore very expensive. If a 1-frame memory is not used, time base conversion must be performed since the input television signal and the printing signal have different time bases. The time base conversion may be performed by adjusting the ratio of input and output clocks of an analog shift register. However, when this method is adopted, the number of the sampling picture elements of the input signal becomes the same as that of the output signal. In other words, the number of sampling picture elements of an input signal determines that of an output signal, thus limiting the size of the output image. In order to produce an image of a larger size, the obtained output picture elements must be interpolated, which requires a complex processing circuit.
When time base conversion is performed including the case of printing with an image signal, the number of sampling picture elements of an input signal coincides with that of an output signal.